1. Field of the Invention
The present invention relates to a magnetic heat pump system and to an air-conditioning system which uses that system.
2. Description of the Related Art
Known in the art is a magnetic heat pump system (also called a “magnetic refrigerating system”) which uses a magnetocalorific material as a work element. A magnetic heat pump system, compared with a refrigeration technique which utilizes conventional gas compression and expansion, that is, a gas heat pump system, does not use Freon or Freon alternatives, so is environmentally friendly. Further, in a magnetic heat pump system, the compression process or the expansion process using a compressor which was necessary for the gas heat pump system is unnecessary, so the energy efficiency is high. The only components which are required for a magnetic heat pump system are a pump which runs a fluid through a magnetocalorific effect material for heat exchange and a magnetic field applying device which imparts a change in magnetic field to the magnetocalorific effect material.
A magnetocalorific effect material which is used for a magnetic heat pump system has the characteristic of changing in temperature when a magnetic field is applied. Explained in further detail, a magnetocalorific effect material exhibits the phenomenon of becoming warmer when a magnetic field is applied and of becoming cooler when the magnetic field is removed (magnetocalorific effect). A rotary magnet type magnetic refrigerator which uses such a magnetocalorific material is disclosed in Japanese Patent No. 4284183. Further, it is known to apply a magnetic heat pump system to a vehicular air-conditioning system, for example, a heat pump system of an air-conditioning system of an automobile or railroad car.